In a semiconductor manufacturing apparatus, when a substrate, for example, a wafer is transported, there is a case where: the wafer is fixed by a holding part (substrate holding claw) so as to prevent the wafer from being moved; and then is transported. In this case, one of the methods of fixing a wafer is fixing a wafer by sandwiching the wafer from one side or both sides. This method of fixing the wafer, in many cases, employs a structure in which an edge portion of the wafer is received by a holding part slanted to an obverse surface or a reverse surface of the wafer in order to minimize a portion in contact with the wafer. In this structure, when the wafer is sandwiched, the slanted holding part and the edge portion of the wafer slide relatively to each other. At this time, depending on the shape of surface of the holding part or the edge portion of the wafer, there is a case where: the wafer is not slid smoothly on the holding part; but is caught in the middle of the holding part. When the wafer is caught in the holding part in this manner, there is a case where a failure of the wafer to be fixed or damage to the wafer is caused. From these problems, it is desirable that the surface of the holding part is machined smoothly so as to decrease bumps and dents to the utmost to thereby reduce friction. Further, it is desirable that the shape of the edge portion of the wafer is machined in a shape in which the edge portion is hard to be caught in the holding part.
In the SEMI standard, the shape of an edge portion of a wafer is defined within a range having an allowance, so if necessary, within the range of the SEMI standard, the shape of the edge portion can be changed into a shape in which the edge portion is hard to be caught in the holding part. For this reason, in the conventional art, as far as the wafer based on the SEMI standard is used, if the holding part is machined in roughness of some extent, the wafer is slid smoothly and hence the failure of the wafer to be fixed or damage to the wafer is hardly caused.
However, in recent years, in a three-dimensional lamination technique of a semiconductor, there is a case where a wafer whose edge portion has a shape sharper than a wafer based on the SEMI standard is used. For example, in a wafer having a structure in which a thin silicon wafer is held by a glass substrate, it is difficult to machine its edge portion in a round shape. In this wafer, when a holding part in the conventional art is used, the wafer is not slid smoothly and hence the failure of the wafer to be fixed or damage to the wafer is caused. As a method of preventing this problem can be smoothly finishing the surface of the holding part by more accurate machining, but the method requires a longer time for machining the holding part, which hence presents problems of a reduction in productivity and an increase in cost. As another method of preventing the problem can be forming a smooth surface on the holding part by die forming, but if a considerable number of holding parts are not mass-produced, the method increases a manufacturing cost.